Question

A public data member may be declared a friend of a private function. a)true b)false

Answer 1

A public data member cannot be declared a friend of a private function. The purpose of declaring a friend function is to grant access to private members of a class.

Step-by-step explanation:

A public data member cannot be declared a friend of a private function. The purpose of declaring a friend function is to grant access to private members of a class. However, a public data member is already accessible outside the class, so there is no need to declare it as a friend of a private function.

For example, consider the following code:

class MyClass
{
private:
int x;
public:
void setX(int val)
{
x = val;
}
friend void displayX(MyClass obj);
};

void displayX(MyClass obj)
{
std::cout << obj.x << std::endl;
}

int main()
{
MyClass obj;
obj.setX(5);
displayX(obj);
return 0;
}
In this code, the function displayX is declared as a friend of the MyClass class. This allows the function to access the private member x of the class. Since x is a private member, it cannot be accessed directly from outside the class, but the friend function displayX can access it.

However, if x was declared as a public data member of the class, there would be no need to declare displayX as a friend of the class, as x can already be accessed directly from outside the class.